Google Translate:
The S55 engine is hot and is based on the basic features of the N55. However, the CCT is reinforced with several ribs to the higher boost pressure into account. Furthermore, other pistons, connecting rods, crankshafts, valves, valve seats, including a different injection system and a completely different principle loaders provide further differentiation! So you can already speak of a completely separate motor, which will be fitted. Performance will be about 440 hp and run tests just last vote ...

Also there is news on V6:
Some still haunts the story about, you would experience the V6 a little later.
This is not so! The V6 project with the name "Apollo" was finally closed after exactly 20 experimental units built. All derivatives M3 (Sedan, GT Coupe, grand coupe and convertible) will all be driven by one and the same S55

CONCLUSION (based on above):
So, it won't sound like a Chevy Celebrity after all?
That is a relief to me, I must admit.

Google Translate:
The S55 engine is hot and is based on the basic features of the N55. However, the CCT is reinforced with several ribs to the higher boost pressure into account. Furthermore, other pistons, connecting rods, crankshafts, valves, valve seats, including a different injection system and a completely different principle loaders provide further differentiation! So you can already speak of a completely separate motor, which will be fitted. Performance will be about 440 hp and run tests just last vote ...

Also there is news on V6:
Some still haunts the story about, you would experience the V6 a little later.
This is not so! The V6 project with the name "Apollo" was finally closed after exactly 20 experimental units built. All derivatives M3 (Sedan, GT Coupe, grand coupe and convertible) will all be driven by one and the same S55

I translate the text here before:
Sporting flagship of the BMW 3 Series remains the BMW M3, the beginning of 2013, with the dealers. While still built sports coupe and convertible version with a V8 high-rev engine is to attract customers, the new M3 is a turbocharged six-cylinder provide the appropriate propulsion. Only the rear wheels are driven, to get an adaptive suspension option, a double-clutch transmission and the head-up display for displaying information in direct view of the driver.

The new one has a different crankcase and a special cylinder head. He developed by M GmbH The performance is even up a gear: Currently expected to be 440 hp. This is the average consumption, which is now at 12.4 liters (manual transmission) to fall at least a liter. As an extra, there's been like the double clutch transmission (DCT Drivelogic). We look forward to the first exit.